Centrifugal blower with cooling function

ABSTRACT

A centrifugal blower with a cooling function includes an impeller, a scroll casing, and an evaporator. The impeller includes a plurality of blades provided around a rotary shaft and blows out in a radially outward direction air taken in along the axial direction of the rotary shaft. The scroll casing accommodates the impeller, and has an intake port, a spiral air passage, and a discharge port. The evaporator is disposed in the air passage of the scroll casing. The evaporator includes a plurality of refrigerant passage members which are stacked in the longitudinal direction of the rotary shaft of the impeller and each of which has a refrigerant flow channel. An air-passing clearance is provided between adjacent refrigerant passage members. The centrifugal blower with a cooling function is used for a vehicle air conditioner.

BACKGROUND OF THE INVENTION

The present invention relates to a centrifugal blower with a cooling function used for a vehicle air conditioner which is mounted on, for example, an automobile.

FIG. 6 shows a conventionally used vehicle air conditioner (see Japanese Patent Application Laid-Open (kokai) No. 2002-144848). The vehicle air conditioner, which is denoted by a reference numeral 51, includes an air conditioner casing 52 having an air introduction port 53, an air blowing port 54, and an air passage 55 which establishes communication between the air introduction port 53 and the air blowing port 54; and an evaporator 56 which is disposed in the air passage 55 of the air conditioner casing 52 and which constitutes a refrigeration cycle. The air passage 55 of the air conditioner casing 52 has a first portion 57 whose upstream end communicates with the air introduction port 53; a second portion 58 in which air flows in a direction orthogonal to the flow direction of air within the first portion 57 and whose downstream end communicates with the air blowing port 54; and a connection portion 59 which is provided at a location where an extension line extending from the first portion 57 in the downstream direction with respect to the air flow direction intersects with an extension line extending from the second portion 58 in the upstream direction with respect to the air flow direction. The connection portion 59 establishes communication between the first portion 57 and the second portion 58, and guides the air having flowed through the first portion 57 to flow into the second portion 58 while changing the flow direction of the air. The air introduction port 53 of the air conditioner casing 52 is connected to a discharge port of a blower 60, and the evaporator 56 is disposed in an upstream region of the second portion 58 of the air passage 55. The evaporator 56 has air-passing clearances through which air passes in a direction parallel to the flow direction of air in the second portion 58.

However, the vehicle air conditioner 51 disclosed in the publication has a problem in that since the evaporator 56 is disposed at the second portion 58 of the air passage 55 of the air conditioner casing 52, the distance between the wall surface 59 a of the connection portion 59 located opposite the second portion 58 and the end of the second portion 58 located on the side toward the air blowing port 54 is relatively large, whereby the size of the vehicle air conditioner 51 becomes relatively large.

SUMMARY OF THE INVENTION

An object of the present invention is to solve the above-mentioned problem and to provide a centrifugal blower with a cooling function which can reduce the size of a vehicle air conditioner.

To fulfill the above object, the present invention comprises the following modes.

1) A centrifugal blower with a cooling function comprising an impeller which includes a plurality of blades provided around a rotary shaft and which blows out in a radially outward direction air taken in along an axial direction of the rotary shaft; a scroll casing which accommodates the impeller and which has an intake port for taking in air along the axial direction of the rotary shaft of the impeller, a spiral air passage through which the air blown out from the impeller flows, and a discharge port for blowing out the air having flowed through the air passage; and an evaporator which is disposed in the air passage of the scroll casing and which has a refrigerant flow channel and an air-passing clearance through which the air flowing through the air passage passes.

2) A centrifugal blower with a cooling function according to par. 1), wherein the evaporator includes a plurality of refrigerant passage members stacked in the longitudinal direction of the rotary shaft of the impeller, the refrigerant flow channel is provided in each of the refrigerant passage members, and the air-passing clearance is provided between adjacent refrigerant passage members.

3) A centrifugal blower with a cooling function according to par. 2), wherein the refrigerant flow channels of the refrigerant passage members of the evaporator are formed such that refrigerant flows through the refrigerant flow channels in a direction opposite the flow of air within the air passage of the scroll casing.

4) A centrifugal blower with a cooling function according to par. 3), wherein each of the refrigerant passage members of the evaporator is formed by joining two metal plates; each refrigerant flow channel is formed by a plurality of flow-channel-forming bulging portions provided on the first metal plate such that they are spaced from one another in the flow direction of air within the air passage of the scroll casing, and a plurality of flow-channel-forming bulging portions provided on the second metal plate such that they are spaced from one another in the flow direction of air within the air passage of the scroll casing and partially overlap with the flow-channel-forming bulging portions of the first metal plate; and the air-passing clearance is formed between two adjacent refrigerant passage members by joining together the flow-channel-forming bulging portions of the first metal plate of one of the two refrigerant passage members and the flow-channel-forming bulging portions of the second metal plate of the other refrigerant passage member.

5) A centrifugal blower with a cooling function according to par. 4), wherein the evaporator has a refrigerant inlet header with which upstream ends of the refrigerant flow channels of all the refrigerant passage members communicate, and a refrigerant outlet header with which downstream ends of the refrigerant flow channels of all the refrigerant passage members communicate; the refrigerant inlet header and the refrigerant outlet header are formed by an inlet header forming portion and an outlet header forming portion, respectively, provided on each refrigerant passage member; the inlet header forming portion is formed by communicatably joining together adjacent ones of inlet header bulging portions provided on the two metal plates of each refrigerant passage member, and the outlet header forming portion is formed by communicatably joining together adjacent ones of outlet header bulging portions provided on the two metal plates of each refrigerant passage member; and the flow-channel-forming bulging portion provided on the first metal plate of each refrigerant passage member at the downstream end thereof with respect to the flow direction of air within the air passage of the scroll casing communicates with the inlet header bulging portion of the first metal plate, the flow-channel-forming bulging portion provided on the first metal plate at the upstream end thereof with respect to the flow direction of air does not communicate with the outlet header bulging portion of the first metal plate, the flow-channel-forming bulging portion provided on the second metal plate at the upstream end thereof with respect to the flow direction of air within the air passage of the scroll casing communicates with the outlet header bulging portion of the second metal plate, and the flow-channel-forming bulging portion provided on the second metal plate at the downstream end thereof with respect to the flow direction of air does not communicate with the inlet header bulging portion of the second metal plate.

6) A centrifugal blower with a cooling function according to par. 5), wherein water drain holes in the shape of through holes are formed in portions of the two metal plates of each refrigerant passage member where the flow-channel-forming bulging portions, the inlet header bulging portion, and the outlet header bulging portion are not provided.

7) A centrifugal blower with a cooling function according to par. 4), wherein each refrigerant passage member has a circular outer shape and has an eccentric circular hole; the evaporator is disposed in the air passage of the scroll casing such that the impeller is located within the eccentric circular hole of each refrigerant passage member; and the flow-channel-forming bulging portions of the first metal plate are straight and incline radially outward toward the downstream side with respect to the flow direction of air within the air passage, and the flow-channel-forming bulging portions of the second metal plate are straight and incline radially outward toward the upstream side with respect to the flow direction of air within the air passage.

The centrifugal blower with a cooling function according to any one of pars. 1) to 7) includes an impeller which includes a plurality of blades provided around a rotary shaft and which blows out in a radially outward direction air taken in along an axial direction of the rotary shaft; a scroll casing which accommodates the impeller and which has an intake port for taking in air along the axial direction of the rotary shaft of the impeller, a spiral air passage through which the air blown out from the impeller flows, and a discharge port for blowing out the air having flowed through the air passage; and an evaporator which is disposed in the air passage of the scroll casing and which has a refrigerant flow channel and an air-passing clearance through which the air flowing through the air passage passes. Therefore, when air forced by the impeller to flow through the air passage of the scroll casing passes through the air-passing clearance of the evaporator, the air is cooled by the refrigerant flowing through the refrigerant flow channel of the evaporator, and the cooled air is blown out from the discharge port of the scroll casing. Accordingly, as compared with the case where an evaporator is separately prepared and is disposed within the air conditioner casing, the size of the air conditioner casing can be reduced. As a result, the overall size of the vehicle air conditioner can be reduced as compared with the vehicle air conditioner described in the above-mentioned publication.

According to the centrifugal blower with a cooling function of par. 2), the evaporator includes a plurality of refrigerant passage members stacked in the longitudinal direction of the rotary shaft of the impeller, the refrigerant flow channel is provided in each of the refrigerant passage members, and the air-passing clearance is provided between adjacent refrigerant passage members. Accordingly, the refrigerant flow channels and the air-passing clearances can be provided in the evaporator relatively easily.

According to the centrifugal blower with a cooling function of par. 3), the efficiency of heat exchange between the air flowing through the air-passing clearances and the refrigerant flowing through the refrigerant flow channels of the refrigerant passage members is improved.

According to the centrifugal blower with a cooling function of par. 4), the heat exchange section of the evaporator can be formed by using two metal plates only without use of separate fins.

According to the centrifugal blower with a cooling function of par. 6), condensed water which is produced on the surface of each refrigerant passage member upon operation of the evaporator can be drained.

According to the centrifugal blower with a cooling function of par. 7), the flow-channel-forming bulging portions extending in different directions are provided in the air-passing clearances, whereby a turbulent flow effect can be imparted to the flow of air.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a view schematically showing a vehicle air conditioner which includes a centrifugal blower with a cooling function according to the present invention;

FIG. 2 is a horizontal sectional view showing the centrifugal blower with a cooling function according to the present invention;

FIG. 3 is an enlarged sectional view taken along line A-A of FIG. 2;

FIG. 4 is a perspective view of an evaporator disposed in the centrifugal blower with a cooling function shown in FIG. 2;

FIG. 5 is an exploded perspective view of a refrigerant passage member used in the evaporator shown in FIG. 4; and

FIG. 6 is a view schematically showing a conventional vehicle air conditioner.

DESCRIPTION OF THE PREFERRED EMBODIMENT

An embodiment of the present invention will next be described with reference to the drawings.

In the following description, the term “aluminum” encompasses aluminum alloys in addition to pure aluminum. Also, in the following description, the upper and lower sides of FIG. 3 will be referred to as “upper” and “lower,” respectively.

FIG. 1 schematically shows a vehicle air conditioner which includes a centrifugal blower with a cooling function according to the present invention. FIGS. 2 and 3 show the centrifugal blower with a cooling function, and FIGS. 4 and 5 show the structure of an evaporator used in the centrifugal blower with a cooling function.

As shown in FIG. 1, a vehicle air conditioner 1 includes an air conditioner casing 2 which is made of plastic and which has an air introduction port 3, an air blowing port 4, and an air passage 5 extending between the air introduction port 3 and the air blowing port 4; and a centrifugal blower 10 which has a cooling function and which blows cooled air into the air introduction port 3 of the air conditioner casing 2.

The air introduction port 3 and the air blowing port 4 of the air conditioner casing 2 are directed toward respective directions which form a predetermined angle (right angle in the present embodiment) therebetween, and the air passage 5 guides the air introduced from the air introduction port 3 to flow toward the air blowing port while changing the flow direction halfway.

Although not illustrated in the drawings, as is well known, the air blowing port 4 of the air passage 5 of the air conditioner casing 2 communicates with air outlets which are formed in the air conditioner casing 2 so as to blow air toward different regions within the vehicle compartment. Air outlets from which air is to be blown out are chosen by a blowing position changeover apparatus. Furthermore, a heater core is also disposed in the air passage 5 of the air conditioner casing 2, and the temperature of the air blown out from the air outputs is adjusted by appropriate means.

As shown in FIGS. 2 and 3, the centrifugal blower 10 includes an impeller 11, a scroll casing 14, and an evaporator 18. The impeller 11 includes a plurality of blades 13 provided around a vertically extending rotary shaft 12. The impeller 11 takes in air along the axial direction of the rotary shaft 12 (from the upper side with respect to the axial direction) and blows the air in a radially outward direction. The scroll casing 14, which accommodates the impeller 11, has an intake port 15 for introducing air from the upper side with respect to the axial direction of the rotary shaft 12 of the impeller 11, a spiral air passage 16 through which the air blown out of the impeller 11 flows, and a discharge port 17 for blowing out the air having flowed through the air passage 16. The evaporator 18 is disposed in the air passage 16 of the scroll casing 14. The discharge port 17 of the scroll casing 14 is connected to the air introduction port 3 of the air conditioner casing 2. The evaporator 18 forms a refrigeration cycle in cooperation with a compressor, a refrigerant cooler (condenser), a pressure reducer, etc.

As shown in FIGS. 2 to 4, the evaporator 18 is formed by stacking a plurality of refrigerant passage members 20 in the longitudinal direction of the rotary shaft 12 of the impeller 11 (the vertical direction) and joining them together. The evaporator 18 has a refrigerant inlet header 21, a refrigerant outlet header 23, and a plurality of refrigerant flow channels 25. The refrigerant inlet header 21 extends in the vertical direction and has a refrigerant inlet 22 which is formed at the upper end thereof and is exposed to the outside of the scroll casing 14. The refrigerant outlet header 23 extends in the vertical direction and has a refrigerant outlet 24 which is formed at the lower end thereof and is exposed to the outside of the scroll casing 14. The refrigerant flow channels 25 establish communication between the refrigerant inlet header 21 and the refrigerant outlet header 23. In a region between the refrigerant inlet header 21 and the refrigerant outlet header 23, air-passing clearances 39 are provided such that each air-passing clearance 39 is located between adjacent refrigerant passage members 20. The refrigerant inlet header 21 of the evaporator 18 is provided on the downstream side (with respect to the flow direction of air) of the air passage 16 of the scroll casing 14 to be located near the discharge port 17. The refrigerant outlet header 23 of the evaporator 18 is provided on the upstream side (with respect to the flow direction of air) of the air passage 16. Each refrigerant flow channel 25 is provided in the corresponding refrigerant passage member 20 such that one end of the refrigerant flow channel 25 communicates with the refrigerant inlet header 21 and the other end of the refrigerant flow channel 25 communicates with the refrigerant outlet header 23.

Each of the refrigerant passage members 20 of the evaporator 18 is formed by joining (by, for example, brazing) two circular aluminum plates 26 and 27 having eccentric circular holes 28 and 29. Each refrigerant passage member 20 has an inlet header forming portion 31 for forming the refrigerant inlet header 21 and an outlet header forming portion 32 for forming refrigerant outlet header 23. The refrigerant flow channel 25 of the evaporator 18 is provided in each refrigerant passage member 20 such that communication is established between the inlet header forming portion 31 and the outlet header forming portion 32, and refrigerant flows in the direction opposite the flow direction of air within the air passage 16 of the scroll casing 14. The evaporator 18 is disposed in the air passage 16 of the scroll casing 14 such that the impeller 11 is located within the eccentric circular holes 28 of the upper and lower aluminum plates 26 and 27 of each refrigerant passage member 20.

As shown in FIG. 5, the inlet header forming portion 31 of each refrigerant passage member 20 is composed of an inlet header upward bulging portion 33 provided on a first aluminum plate 26 (first metal plate) located on the upper side in the present embodiment such that the inlet header upward bulging portion 33 bulges upward, and an inlet header downward bulging portion 34 provided on a second aluminum plate 27 (second metal plate) located on the lower side in the present embodiment such that the inlet header downward bulging portion 34 bulges downward at a position corresponding to that of the inlet header upward bulging portion 33. The outlet header forming portion 32 of each refrigerant passage member 20 is composed of an outlet header upward bulging portion 35 provided on the first aluminum plate 26 such that the outlet header upward bulging portion 35 bulges upward, and an outlet header downward bulging portion 36 provided on a the second aluminum plate 27 such that the outlet header downward bulging portion 36 bulges downward at a position corresponding to that of the outlet header upward bulging portion 35.

The refrigerant flow channel 25 of each refrigerant passage member 20 is formed by a plurality of flow-channel-forming upward bulging portions 37 which are provided on the first aluminum plate 26 such that they are spaced from one another in the flow direction of air within the air passage 16 of the scroll casing 14 and they budge upward, and a plurality of flow-channel-forming downward bulging portions 38 which are provided on the second aluminum plate 27 such that they are spaced from one another in the flow direction of air within the air passage 16 of the scroll casing 14 and they budge downward and such that they partially overlap with the flow-channel-forming upward bulging portions 37 of the first aluminum plate 26. The flow-channel-forming upward bulging portions 37 of the first aluminum plate 26 are straight and incline radially outward toward the downstream side with respect to the flow direction of air within the air passage 16. The flow-channel-forming downward bulging portions 38 of the second aluminum plate 27 are straight and incline radially outward toward the upstream side with respect to the flow direction of air within the air passage 16. When viewed from above, each flow-channel-forming upward bulging portion 37 of the first aluminum plate 26 partially overlaps with at least one flow-channel-forming downward bulging portion 38 of the second aluminum plate 27, whereby the refrigerant flow channel 25 is formed between the two aluminum plates 26 and 27 of each refrigerant passage member 20.

The flow-channel-forming upward bulging portion 37 provided on the first aluminum plate 26 of each refrigerant passage member 20 at the downstream end with respect to the flow direction of air within the air passage 16 of the scroll casing 14 communicates with the inlet header upward bulging portion 33 of the first aluminum plate 26, and the flow-channel-forming upward bulging portion 37 provided on the first aluminum plate 26 at the upstream end with respect to the flow direction of air does not communicates with the outlet header upward bulging portion 35 of the first aluminum plate 26. The flow-channel-forming downward bulging portion 38 provided on the second aluminum plate 27 at the upstream end with respect to the flow direction of air within the air passage 16 of the scroll casing 14 communicates with the outlet header downward bulging portion 36 of the second aluminum plate 27, and the flow-channel-forming downward bulging portion 38 provided on the second aluminum plate 27 at the downstream end with respect to the flow direction of air does not communicates with the inlet header upward bulging portion 34 of the second aluminum plate 27.

Accordingly, in each refrigerant passage member 20, refrigerant entering through the inlet header upward bulging portion 33 of the first aluminum plate 26 enters the flow-channel-forming upward bulging portion 37 communicating with the inlet header upward bulging portion 33, then flows through the flow-channel-forming downward bulging portions 38 of the second aluminum plate 27 and the flow-channel-forming upward bulging portions 37 of the first aluminum plate 26 alternately, enters the flow-channel-forming downward bulging portion 38 provided on the second aluminum plate 27 at the upstream end with respect to the flow direction of air within the air passage 16 of the scroll casing 14, and enters the outlet header downward bulging portion 36.

The inlet header upward bulging portion 33, outlet header upward bulging portion 35, and flow-channel-forming upward bulging portions 37 of the first aluminum plate 26 of each refrigerant passage member 20 have the same bulging height, and the inlet header downward bulging portion 34, outlet header downward bulging portion 36, and flow-channel-forming downward bulging portions 38 of the second aluminum plate 27 of each refrigerant passage member 20 have the same bulging height. All the refrigerant passage members 20 are assembled and brazed together such that between two adjacent refrigerant passage members 20, bulging end portions of the inlet header downward bulging portion 34 and outlet header downward bulging portion 36 of the second aluminum plate 27 of the upper refrigerant passage member 20 are brazed to bulging end portions of the inlet header upward bulging portion 33 and outlet header upward bulging portion 35 of the first aluminum plate 26 of the lower refrigerant passage member 20, and bulging end portions of the flow-channel-forming downward bulging portions 38 of the second aluminum plate 27 of the upper refrigerant passage member 20 are brazed to bulging end portions of the flow-channel-forming upward bulging portions 37 of the first aluminum plate 26 of the lower refrigerant passage member 20. The inlet header forming portions 31 of all the refrigerant passage members 20 are communicatably connected together, and the outlet header forming portions 32 of all the refrigerant passage members 20 are communicatably connected together, whereby the refrigerant inlet header 21 and the refrigerant outlet header 23 are formed. A air-passing clearance 39 is formed between two adjacent refrigerant passage members 20 by the flow-channel-forming downward bulging portions 38 of the second aluminum plate 27 of the upper refrigerant passage member 20 and the flow-channel-forming upward bulging portions 37 of the first aluminum plate 26 of the lower refrigerant passage member 20. The air which flows within the air passage 16 of the scroll casing 14 passes through the air-passing clearance 39.

Through holes 41 and 42 for draining water are formed in the first aluminum plate 26 and second aluminum plate 27 of each refrigerant passage member 20 such that the positions of the through holes 41 correspond to those of the through holes 42, and the through holes 41 and 42 are deviated from the various bulging portions 33, 34, 35, 36, 37, and 38.

When the vehicle air conditioner 1 is used for cooling, a compressor is operated and the impeller 11 of the centrifugal blower with a cooling function is rotated. Low pressure, two-phase refrigerant (a mixture of gas-phase refrigerant and liquid-phase refrigerant) having been compressed by the compressor and having passed through a condenser and an expansion valve flows through the refrigerant inlet 22 of the evaporator 18 of the centrifugal blower, enters the refrigerant inlet header 21, flows through the refrigerant flow channel 25 of each refrigerant passage member 20, enters the refrigerant outlet header 23, and flows out from the refrigerant outlet 24. Meanwhile, as a result of the impeller 11 being rotated, air is taken in through the intake port 15 of the scroll casing 14, enters the air passage 16, passes through the air-passing clearances 39 of the evaporator 18, flows through the air passage 16, and is blown out from the discharge port 17. While flowing through the refrigerant flow channels 25 of the refrigerant passage members 20, the refrigerant exchanges heat with the air which passes through the air-passing clearances 39 as a result of rotation of the impeller 11. The refrigerant flows out in the gas phase, and the air is cooled.

The cooled air is fed into the air passage 5 of the air conditioner casing 2 through the air introduction port 3, flows through the air blowing port 4, and is blown out from the air outlets formed in the air conditioner casing 2 toward different regions within the vehicle compartment.

The evaporator used in the centrifugal blower with a cooling function according to the present invention is not limited to that shown in FIGS. 2 to 5.

In the above-described embodiment, the refrigerant inlet 22 is formed at the upper end of the refrigerant inlet header 21, and the refrigerant outlet 24 is formed at the lower end of the refrigerant outlet header 23. However, the positions of the refrigerant inlet 22 and the refrigerant outlet 24 are not limited thereto, and the embodiment may be modified such that the refrigerant inlet 22 is formed at the lower end of the refrigerant inlet header 21, and the refrigerant outlet 24 is formed at the upper end of the refrigerant outlet header 23. Alternatively, the refrigerant inlet 22 and the refrigerant outlet 24 may be formed at the upper ends of the refrigerant inlet header 21 and the refrigerant outlet header 23 or the lower ends of the refrigerant inlet header 21 and the refrigerant outlet header 23. 

What is claimed is:
 1. A centrifugal blower with a cooling function comprising: an impeller which includes a plurality of blades provided around a rotary shaft and which blows out in a radially outward direction air taken in along an axial direction of the rotary shaft; a scroll casing which accommodates the impeller and which has an intake port for taking in air along the axial direction of the rotary shaft of the impeller, a spiral air passage through which the air blown out from the impeller flows, and a discharge port for blowing out the air having flowed through the air passage; and an evaporator which is disposed in the air passage of the scroll casing and which has a refrigerant flow channel and an air-passing clearance through which the air flowing through the air passage passes.
 2. A centrifugal blower with a cooling function according to claim 1, wherein the evaporator includes a plurality of refrigerant passage members stacked in the longitudinal direction of the rotary shaft of the impeller, the refrigerant flow channel is provided in each of the refrigerant passage members, and the air-passing clearance is provided between adjacent refrigerant passage members.
 3. A centrifugal blower with a cooling function according to claim 2, wherein the refrigerant flow channels of the refrigerant passage members of the evaporator are formed such that refrigerant flows through the refrigerant flow channels in a direction opposite the flow of air within the air passage of the scroll casing.
 4. A centrifugal blower with a cooling function according to claim 3, wherein each of the refrigerant passage members of the evaporator is formed by joining two metal plates; each refrigerant flow channel is formed by a plurality of flow-channel-forming bulging portions provided on the first metal plate such that they are spaced from one another in the flow direction of air within the air passage of the scroll casing, and a plurality of flow-channel-forming bulging portions provided on the second metal plate such that they are spaced from one another in the flow direction of air within the air passage of the scroll casing and partially overlap with the flow-channel-forming bulging portions of the first metal plate; and the air-passing clearance is formed between two adjacent refrigerant passage members by joining together the flow-channel-forming bulging portions of the first metal plate of one of the two refrigerant passage members and the flow-channel-forming bulging portions of the second metal plate of the other refrigerant passage member.
 5. A centrifugal blower with a cooling function according to claim 4, wherein the evaporator has a refrigerant inlet header with which upstream ends of the refrigerant flow channels of all the refrigerant passage members communicate, and a refrigerant outlet header with which downstream ends of the refrigerant flow channels of all the refrigerant passage members communicate; the refrigerant inlet header and the refrigerant outlet header are formed by an inlet header forming portion and an outlet header forming portion, respectively, provided on each refrigerant passage member; the inlet header forming portion is formed by communicatably joining together adjacent ones of inlet header bulging portions provided on the two metal plates of each refrigerant passage member, and the outlet header forming portion is formed by communicatably joining together adjacent ones of outlet header bulging portions provided on the two metal plates of each refrigerant passage member; and the flow-channel-forming bulging portion provided on the first metal plate of each refrigerant passage member at the downstream end thereof with respect to the flow direction of air within the air passage of the scroll casing communicates with the inlet header bulging portion of the first metal plate, the flow-channel-forming bulging portion provided on the first metal plate at the upstream end thereof with respect to the flow direction of air does not communicate with the outlet header bulging portion of the first metal plate, the flow-channel-forming bulging portion provided on the second metal plate at the upstream end thereof with respect to the flow direction of air within the air passage of the scroll casing communicates with the outlet header bulging portion of the second metal plate, and the flow-channel-forming bulging portion provided on the second metal plate at the downstream end thereof with respect to the flow direction of air does not communicate with the inlet header bulging portion of the second metal plate.
 6. A centrifugal blower with a cooling function according to claim 5, wherein water drain holes in the shape of through holes are formed in portions of the two metal plates of each refrigerant passage member where the flow-channel-forming bulging portions, the inlet header bulging portion, and the outlet header bulging portion are not provided.
 7. A centrifugal blower with a cooling function according to claim 4, wherein each refrigerant passage member has a circular outer shape and has an eccentric circular hole; the evaporator is disposed in the air passage of the scroll casing such that the impeller is located within the eccentric circular hole of each refrigerant passage member; and the flow-channel-forming bulging portions of the first metal plate are straight and incline radially outward toward the downstream side with respect to the flow direction of air within the air passage, and the flow-channel-forming bulging portions of the second metal plate are straight and incline radially outward toward the upstream side with respect to the flow direction of air within the air passage. 